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From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: zip as iterator and bad/good practices
Date: Fri, 12 Jun 2015 19:43:08 -0400
References: <mles66$sk2$1@speranza.aioe.org> <201506122034.t5CKYYt0025588@fido.openend.se>
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On 6/12/2015 4:34 PM, Laura Creighton wrote:
> The real problem is removing things from lists when you are iterating
> over them, not adding things to the end of lists.

One needs to iterate backwards.

 >>> ints = [0, 1, 2, 2, 1, 4, 6, 5, 5]

 >>> for i in range(len(ints)-1, -1, -1):
	if ints[i] % 2:
		del ints[i]
	
 >>> ints
[0, 2, 2, 4, 6]

But using a list comp and, if necessary, copying the result back into 
the original list is much easier.

 >>> ints = [0, 1, 2, 2, 1, 4, 6, 5, 5]
 >>> ints[:] = [i for i in ints if not i % 2]
 >>> ints
[0, 2, 2, 4, 6]


-- 
Terry Jan Reedy